Measurements showed a high impact of process time when doing numerous iterations in a while loop. For approx. 65 thousand iterations the process times are ca. 5 seconds without floating text, 24 seconds with llSetText and 96 seconds when using llSetPrimitiveParams#llSetLinkPrimitiveParamsFast in combination with PRIM_TEXT. Thats why you are not advised to make excessive use of changing a prim's text within such iterations.